Revert "settings: Remove version field migration" (#33729)

- Reverts zed-industries/zed#33711

I think we should just make this a breaking change with v0.194.x.
Forwards compatibility is hard, we should build abstractions that make
this easier (next time).

See also:
- https://github.com/zed-industries/zed/pull/33372

Release Notes:

- N/A

crates/migrator/src/migrations.rs

@@ -82,6 +82,12 @@ pub(crate) mod m_2025_06_16 {
     pub(crate) use settings::SETTINGS_PATTERNS;
 }
 
+pub(crate) mod m_2025_06_25 {
+    mod settings;
+
+    pub(crate) use settings::SETTINGS_PATTERNS;
+}
+
 pub(crate) mod m_2025_06_27 {
     mod settings;